Means for steerably interconnecting vehicles in tandem



Jan. 28, 1964 R. .1. OLIVER MEANS FOR STEERABLY INTERCONNECTING VEHICLESIN TANDEM '7 Sheets-Sheet 1 lll\ m.

Filed Jan. 3, 1961 Jan. 28, 1964 R. J. OLIVER 3,119,639

MEANS FOR STEERABLY INTERCONNECTING VEHICLES IN TANDEM Filed Jan. 3,1961 7 Sheets-Sheet 2 inven or R. J. OLIVER Jan. 23, 1964 MEANS FORSTEERABLY INTERCONNECTING VEHICLES IN TANDEM '7 Sheets-Sheet 3 FiledJan. 5, 1961 NEE QM Ev Maw QQN Jan. 28, 1964 R. J. OLIVER 3,119,630

MEANS FOR STEERABLY INTERCONNECTING VEHICLES IN TANDEM Filed Jan. 5,1961 7 Sheets-Sheet 4 R. J. OLIVER 3,119,630

MEANS FOR STEERABLY INTERCONNECTING VEHICLES IN TANDEM Jan. '28, 1964 7Sheets-Sheet 5 Filed Jan. 3, 1961 2116724071 9 Robert a?) 0Z2 #2? R. J.OLIVER 3,119,630

MEANS FOR STEERABLY INTERCONNECTING VEHICLES IN TANDEM Jan. 28, 1964 7Sheets-Sheet 6 Filed Jan. 3, 1961 R. J. OLIVER Jan. 28, 1 964 MEANS FORSTEERABLY INTERCONNECTING VEHICLES IN TANDEM 7 Sheets-Sheet 7 Filed Jan.3, 1961 w Q 1 5 w w 11 1 8 J0 MW L in a z/ 77 for;

J OZZY/27" United States Patent G 3,119,630 MEANS FOR STEERABLYINTERCONNECTENG VEHICLES IN TANDEM Robert J. liver, Lyons, Ill.,assignor to International Harvester Company, Chicago, Ill., acorporation of New Jersey I y Y Filedllan. 3, 1961, Ser. No. 80,218

' 11 Claims. (Cl. 230*402) This invention relates to tandem connectedcomponents movable alongthe ground, especially tractors, and to meansfor connecting a plurality of components, especially tractors, in tandemand forsteering the same.

A prineipal object of the invention in preferred forms thereof i's'toprovide for the interconnection of a plurality of tractors of the typenormally having spaced forward and rearward ground-engaging supportmeans, such as wheels, in tandem and conversion thereof into a tandemtractor unit in which contact with the ground is only through therearward support means of the tractors.

Another important object is to provide for such interconnection andconversion as above set forth so as not to increase the stresses thestructures of the component tnactors of the unit are under over thosethey are under as separate tractors. More paiticularly, it is an objectto provide for such interconnection and conversion of tractors into aunit as above set forth not only soas not to increase the stresses inthe component tractors of the unit due to 4 bending moments, but also soas not to impose any tappreciable torsional stresses therein which thetractors are not intended to withstand, while operating the unit in acurved path or during turning.

Another object is to provide means for interconnecting tnactors for theproduction of units as above set forth comprising a unitary rigidstructure which is articulated for movement about the vertical andlongitudinally horizontal axes, when the unit is on level ground, andwhich can withstand the great bending moment and torsion to which it issubjected without binding and interfering with relative pivotalmovementof the portions of said structure about said axes.

' A further object is to provide means for interconnecting tractors forthe production of units as above set forth comprising a unitarystructure which can be exceedingly quickly and easily unitarily attachedto and detached from the tractors during formation and disassembly ofthe unit,

respectively. 1

Still another object is to provide interconnecting means betweentractors for the production of the unit as above set forth comp-rising aunitary structure from which the front tractor can be quickly and easilydisconnected in a few seconds for independent use, leaving saidstnucture still connected to the trailing tractor and ready for instantre- COIIIICCCIOII'Wl'lEIl the unit is again desired,

.Yet another object is to provide a tractor unit as above set forth inwhich receiving pocket or stirrup means are carried by the componenttractors into which the aforesaid unitary structune is convenientlyslipped and pinned during interconnection of the tractors and from whichit-is quickly removed by knocking out the pins during disassembly of theunit.

A still further object is to provide rugged, simple, compact, andeffective interconnecting means between the tnactors of the unit asabove set forth which cannot become sprung or otherwise damagedby theroughest possible use.

Another object of great importance is to provide a tandem tractor unitin which the steeering wheel of the second tractor controls the steeringof the unit through the means interconnecting the tractors in tandem.

A further object of great significance is to provide a tandem tractorunit in which the steering wheel of the second tractor controls thesteering of the unit through the ent I964 ice will prevent the settingup of objectionable and destructive chattering or harmonic vibrations,such chattering or vibrations being prevented by a structure in whichthe control valve means of said fluid actuated means is connecteddirectly to one of the portions of the means for connecting the tractorsand further in which the control valve means senses only relativemovement between the tractors inthe horizontal plane which is the onlysensing desired, the latter functioning in-and thereby being necessaryto the steering action of the .tandemized-tractors.

Other objects, advantages, and featuresof theinvention will appear from.the following illustnative description, read with the accompanyingdrawing, in which:

FIGURES 1 and 1A constitute a side-,elevational view of a tractor unitembodying a preferred form of the present invention;

FIGURES 2 and 2A constitute a top plan view of the unit of FIGURES 1 and1A with the two tractors being shown in phantom lines for, convenienceof illustration and of viewing; A 7

FIGURE 3 is an enlarged fragmentary side-elevational view of a midportion of the unit of FIGURES 1 and 1A; FIGURE 4 is a fragmentarysectional view taken on line 44 of FIGURE 3 and in the direction of thearrows;

FIGURE 5 is an enlarged fnagmentary top plan view of the mid portion oftheunit shown in FIGURE 3 with the rear' tractor omitted and certainparts shown bnoken ofi for. convenience of illustration and viewing.FIGURE 6 is a fragmentary portion of FIGURE 5 with the parts which arebroken off in the. latter figure being shown and other parts beingomitted for convenience of illustration and of viewing;

*FIGURE 7 is an enlarged view taken on line 77 of FIGURE 1A and in thedirection of the arrows;

FIGURE 8.is an enlarged view taken on line 8-8 of FIGURE 1A and in thedirection of the arrows;

FIGURE 9 is an enlarged view taken-on line 9-9 of FIGURE 1 and in thedirection of the arrows;..and

FIGURE 10 is an enlarged fragmentary top plan vie as indicated by line10-10 of FIGURE 1.

Referring to the drawing in detail, the tandem tractor unit thereindepicted comprises a pair of wheeled tractors I and 2 of the type usedon farms, from which the front wheel bolsters and included wheels have.been removed, and interconnecting or tandem hitch means between thetractors generally designated by the numeral 3. The interconnectingmeans includes. a rigid, articulated structure generally designated 4which extends below the rear or trailing tractor 2 and at least .half ofthe front tractor 1, and means for connecting the substructure 4 to thetractors to be. pointed out below. 7

The structure 4 comprises a forward portion generally designated 5extending under the front tractor 1 and a rear portion generallydesignated 6 extending under the rear tractor 2. The front portion 5.has a pair of spaced, parallel, upwardly inclined, longitudinallyextending members 7 of hollow rectangular section of decreasing heightthough constant width, from the rearmost ends to the forward ends of themembers. The members 7' are connected to a U-shaped crossmember 8 bywelding at the rear ends thereof. A pair of side plates 9 are welded tothe opposite sides, respectively, of the member 8 to constitute a crosssupport structure with said member for the members 6. A longitudinallyextending sleeve -11 containing a front and rear bushing 12 and 13 istransversely centrally positioned between the upper and lower flanges ofthe U-shaped member 8, being suitably welded to the member. The webportion of the U-shaped member 8 contains a centrally located circularaperture of sufiicient size to receive the sleeve 11 which extendsthereinto and is welded therearound to the web portion.

The rear portion 6 of the structure 4 comprises a pair of forwardlyextending and converging side members 17 of hollow rectangular sectionof gradually increasing height, though constant width, from the rearmostends to the forward ends of the members. The forward ends of the sidemembers 17 are secured to a vertically extending, centrally bored,cylindrical terminal member 19 by welding. A reinforcing member 20having an upper web portion and depending triangular shaped flangesalong the opposite sides of the latter is joined to the side members 17across the forward ends thereof and to the terminal member 19 weldingalong the several contacting edges thereof. A medially disposed fiatcrossmember 23 is secured to the bottom surfaces of the side members 17by welding. A V-shaped brace member 24 is welded at its forward ends tothe side members 17 and along the bottom edge of the central portionthereof to the crossmember 23. A centrally disposed block or pad element25 is welded to the bottom surface of the crossmember 23 while anL-shaped crossmember 26 having a horizontally disposed forwardlydirected leg spaced below said block 25 is welded to the side members 17and also along the rear edges of the crossmember 23 and block 25, thusforming a elevis with the crossmember 23 and block 25 for a purpose tobe brought out below. A pair of downwardly inclined, forwardlyconverging, flat brace members 27 are additionally welded between theside members 17 and angle iron crossmember 26.

The front portion 5 of the structure 4 further includes a membergenerally designated 29 having a forwardly, A

longitudinally horizontally extending shaft portion 30 received withinthe sleeve 11 of the front portion and extending forwardly therebeyond.A collar 31 is secured to the front end of the shaft portion 30 by meansof a pin 32, the collar abutting against the front surface of the sleeve11 to retain the member 29 within the sleeve 11. The member 29 also hasa yoke portion 34 having spaced, upper and lower rearwardly extending,coaxially vertically bored arm portions 35 and 36 provided with bushings37 and 38. A vertical pin 40 extends through the bores in the portions35 and 36 of the yoke 34 and also through the vertically bored terminalmember 19 of the rear portion 6 of the structure 4, being secured tosaid member by means of a pin 41. Fittings 42 are provided forlubrication of the bearing surfaces of the yoke 34 and pin 40.

It should be apparent that the member 29 and the cooperative parts ofthe front and rear portions 5 and 6 of the structure 4 provide auniversal joint for relative movement of sai portions about the verticaland longitudinally disposed horizontal axes. There is no pivotalmovement, however, about the transverse horizontal axis, normal to thelongitudinal horizontal axis, the structure being substantially rigid inthe longitudinal vertical plane for receiving and withstanding bendingmovements incident to the support of the tractors forward of the rearwheels thereof from which tractors the front bolsters and includedwheels have been removed.

Four pocket or stiriup structures on each side of the tractors 1 and 2,namely 45, 46, 47, and 43 and 49, 50, 51, and 52, which constitute partof the interconnecting means 3, receive the structure 4, the latterbeing connected to each of the structures and consequently to thetractors by means of a single quickly insertable and removablehorizontally disposed pin, as will be brought out below. The forwardpocket or stirrup structures 45 and 49 each comprises a flat plate 54which is aflixed by means of three bolts to a pad 55 on the side of theclutch housing 56 of the front tractor 1, a generally L-shaped bracketmember 57 welded to the plate 54 and extending outwardly therefrom andthen downwardly and an inward guide and side wall member 59 having anupper vertical wall and inwardly inclined lower guide portion 60, thelatter member being suitably welded at the bottom and the top thereof tothe plate 54 and L-shaped bracket member 57, respectively. The outer legof the member 57, the inner member 59, and the plate 54 are allhorizontally coaxially bored, in the lower portions thereof, normal tothe longitudinal axis of the tractor for reception of a singlehorizontally disposed pin 62 therethrough immediately below the receivedside member 7 of the structure 4 for retention of the side member withinthe pocket and consequent connection thereof to the tractor, which pinis secured in place by a quick attach and detach spring tension retainedcotter element 63 located at the inner end of the pin.

The rear pocket structures 46 and 50 connected to the front tractor 1each comprise a pair of spaced plate members 66 and 67 which are weldedto each side of one of a pair of conventional axle carrier brackets 68forming part of the structures 46 and 59, respectively. Each of thelatter brackets briefly consists of spaced, substantially verticallyextending front and rear members 69 and 70 of hollow square and U-shapedconstruction, respectively, between which a pair of bolts extend,clamping said two members to the rear axle carrier or housing 71 of thefront tractor 1. The plate members 66 and 67 are each outwardly crimpedat 73 providing wider lower portions of the pocket structures forrelatively snug reception of the side members 7 of the front portion 5of the structure 4. The bottom portion of each of the members 66 and 67is also outwardly inclined for quickly and conveniently guiding ordirecting the side members 7 into received relation within the pocketstructures. The members 66 and 67 of each of the structures 46 and 50are horizontally coaxially bored normal to the longitudinal axis of thetractor for reception of a single horizontally disposed pin '76 which issecured in place by a quick attach and detach spring tension retainedcotter element 77 as in the case of pins 62 and located at the inner endof the pin. The side members 7 of the structure 4 are also bored forpassage of the pins therethrough when within the pocket structures 46and 50 for connection of the members to the front tractor 1.

The forward pocket or stirrup structures 47 and 51 connected to the reartractor 2 each have an outer plate 79 aflixed to a pad 81 on the side ofthe clutch housing 82 of the tractor by means of three bolts. Each ofthe structures also has an inner plate 84 welded to the plate 79, whichinner plate extends inwardly and then downwardly presenting a verticalWall portion 85. The plates 79 are crimped or offset inwardly to placetheir lower vertical wall portions in positions so as with the Wallportions 85 of the members 84 to relatively snugly receive the members17 of the rear portion 6 of the structure 4. The lower wall portions 86and 85 of each of the structures 47 and 51 are coaxially horizontallybored normal to the longitudinal axis of the tractor for reception of asingle horizontally disposed pin 86 which is secured in place by a quickattach and detach spring tension retained cotter element 37 as in thecase of the pins 62 and located at the inner end of the pin. The lowerportions of the plates 79 are outwardly inclined for guiding receptionof the side members 17 within the pocket structures 47 and 51. The sidemembers 17 of the structure 4 are also bored for passage of the pins 86therethrough when within the pocket structures 47 and 51 for connectionof the members to the rear tractor 2.

The rear pocket structures 48 and 52 connected to the rear tractor 2each comprise a pair of spaced plate members 94' and 95' having inturnedflanges 96 and 97 along their rear edges thereof. The latter'flanges ofeach structure are welded along'each side of oneof a pair of axlecarrier brackets 99 of identical construction to the brackets 68' on thefront tractor and formingpart of the structures 48 and 52. The lowerportions of the plate members 94 and' 95 of each structure 48' and '52are 'coaxially horizontally bored normal to the longitudinal axis of thetractor for reception of a single horizontally disposed pin 161 which issecured in place by a quick attach and detach spring tension retainedcotter element as in the case of pins 62 and located at the inner endsofthe pin. The lower ends of the plate members 94' and 95 are outwardlyinclined to provide guide surfaces for ready ins'erti'on of theniembers17 of the structure 4 therebetween during assembly of thetractor unit. "The side members 17 of the structure 4 are also bored forpassage of the pins 191 'thereth'rough when within the pocket structures48 and 52 for"connection of the members to the rear tractor 2.

A pair of spaced, generally triangular shaped plates 1'03 are welded tothe'inturned flanges 96 and 97 of the plate members 94 and 95 of each ofthe structures 48 and 521 The heavy-duty drawbar 105 is connected to thestructures 48 and 52 between the rearwardly extending spaced plates 103thereof by means of a pair of horizontally disposed pins 106 extendingnormally to the longitudinal axis of the tractor through the pairs ofspaced'plates and received enlarged portions 107 of the drawbar weldedto the forward ends of the side portions of the latter, which pins aresuitably secured in place by quick attach and detach spring tensionretained cotter elements also as in the case of the first-mentioned pins62'. The fonvard enlarged portions 167 of the drawbar and also thespaced plates 1193 are, of course, bored for reception of the pins 1'06;The heavy duty drawbar 105 is additionally connected to the structures48 and 52 by 'a pair of fiatbottomed U-shaped members 168 welded to thed'rawbar on each side thereof and a pair of twisted straps 1139 pinnedat their lower ends to the U-shaped members 108 and removably attachedat their upper ends tothe rearward, U-shaped members 110 of the rearaxle carrier brackets 99 by the usual eyebolts mounted on such carrierbracket members.

The structure 4 carries certain parts for steering the tractor unitwhich cooperate with the steering mechanism of the rear tractor 2. Theseparts includea doubleacting' hydraulic cylinder 117 pivotally connectedat its rear end to the clevis formed by the members 25 and 26 by meansof a verticalpin 11S and pivotally connected at its front end to asteering drive arm l ltl by means of a vertical pin 1 21; The arm 120 ispivotally connected at its inboard end between the lower'inturnedandoutturned flanges of plates 1'22 and 123, respectively, which platesare welded to the outer and inner sides, respectively, of the left-handmember 17 of the structure 4, as viewed from the rear of the tractorunit, by means of a vertical pin 124. The outboard end of the arm 120 ispivotally connected to the rear end ofa link 128 by'means of a' verticalpin 126, the front end of which link is pivotally connected to alaterally extending portion 129 of th'eyoke portion 34 of the frontportion 5 of the structure 4 by means ofa verticalpin 130.

Avalve 133 is' pivotally connected at its rear end to a transverselyextending support lrnember .134'by means of a vertical pin 135 extendingthrough a clevis member 136 threaded onto the end of the valve andthrough the support member received within the clevis, the supportmemher being welded at each side to the opposite side members 17 of therear portion 6' of the structure 4. The valve is connected at its frontend to one end of a transversely extending lever 13% by means of avertical shoulder belt 139 extending through an element :137threadedonto the outer end of the stem of the valve and through the lever.

The opposite or outboard end of the lever 13% is pivotally connected toa link 1 41 by means of a vertical pin 142. The latter link is, in turn,pivotally connected at its opposite end to a depending bracket 143connected to one side of the top portion 35' of the yoke 34' of thestructure 4. The lever 13-8 is pivotally connected intermediate its endsto a steering'arm plate 146 by means of a screw 144 extending through alever abutting washer and threaded into a pivot element 145 which iswelded to the plate 146, the steering arm'plate 146 being Welded to astop plate 147. The steering arm plate 146 and stop plate 147 are boltedas a unit 'to' the bottom of the mounting plate portion or flange'1'48on the lower end of the steeringpivot shaft 150' of the rear tractor 2'by means of two diagonally disposed bolts 149. The pivot shaft isconnected through a pinion 151 thereon to the steering wheel 152 throughthe usual sector 153 and worm, not shown, and universally jointed shaftmeans 1-55. Although the tractor 2 has been disclosed as having amechanical steering mechanism, power steering maybe provided if desired,the present invention being equally cooperable with either steeringmechanism of the tractor. The forward portion of the stop plate 147makes abutting contact with stop elements 156 welded to a supportingmember 157 in turn bolted to the under portion of the tractor 2 adjacentthe front end thereof'so as to limit the amount of turning of the rearWheels 158 of the forward tractor in either direction of thelongitudinal center line of the tractor unit.

Fluid'line 169 connects the valve '133 to the source of hydraulicpressure, not shown, in the forward tractord, leaving the source ofhydraulic pressure of the rear tractor exclusively available foroperation of the machinery or equipment drawn by the tractor unit, whilefluid line 161 connects the valve to the hydraulic reservoir, not shown,of the forward tractor; Fluid lines 163 and 164 extend from the valve133 to the front and rear portions, respectively, of the double actingcylinder 117 for operation of the piston of the cylinder and 'theattached linkage and connected front portion 5 of the structure 4 andfront tractor 1 in the opposite directions of reciprocal movementthereof.

Considering the steering operation of the tractor unit, rotation of thesteering wheel 15 2 of the rear tractor 2 in either direction causescorresponding rotation of the steering pivot shaft 150 and attachedplates 146 and 147, as seen in FIGURE 3. The intermediate pivot 145of'the lever 5133, which is mounted off-center to the left, asvie-wed'fro-m the rear of the tractor unit, from the axis of rotation ofthe pivot shaft 150 and attached plates 146 and 147, in turn, swings inanarc 166 (see FIGURE 6) about said axis in a clockwise orcounterclockwise direction, as seen from above, depending upon thedirection of turn of the steering wheel. inasmuch as the outboard pivot1-42 of the lever 138 is stationary when this swinging movement firsttakes place, the opposite end of the lever swings forwardly andrearwardl-y for clockwise and counterclockwise rotation of the steeringwheel, respectively, thus moving the inner valve member, not shown, ofthe valve 133 so as to internally connect the supply line 1641 with thefluid lines 163 and 164, respectively, thus to initiate movement of thepiston of the cylinder 117 and the connected linkage in a rearward andforward direction, respectively. The rearward and forward force,respectively, on the piston is transmitted through the piston rod andlinks 120 and 128 to the projecting portion 129 of the yoke 34 and fromthence as a clockwise and counterclockwise rotational force,respectively, as seen from above, into the rest of the front portion 5of the structure 4, into the attached front tractor i1, and into therear wheels of said tractor which are the front steering wheels of thefour-wheeled tractor unit. During forward movement of the tractor unitthe above action will obviously cause turning of the unit towards theright and left, respectively.

The inner valve member of the valve i133 has very limited travel, onlymoving a fraction of an inch in each of the opposite directions from aneutral position in which the lines 164} and 161 are connected toneither of the lines 163 or 164, thus to maintain the cylinder 117 andthe connected linkage, from portion of the structure 4, and attachedfront tractor in a state of rest in whatever position the piston of thecylinder, linkage, portion 5 of structure 4, and front tractor may be.Upon even very slight movement of the steering wheel 152, therefore, thevalve member of the valve 133 is moved sufiiciently from its neutralposition to pressurize one or the other parts or sides of the cylinder117 to initiate the pivotal movement of the front portion 5 of thestructure 4 and the attached tractor about the vertical axis through thepivot pin 40 of the frame 4. Upon only slight movement of the steeringWheel 152 in either direction, the rotational movement of the frontportion 5 of the frame 4 is translated to the lever 133 by means of thelink 14 1 whereby to rotate the lever about its intermediate pivotpoint, even while the pivot itself is moving in the abovedescribedarcuate path and move the end 139 of the lever sutficiently to returnthe valve member of the valve 133 to its neutral position and thus toarrest the rotation movement of the front portion 5 of the structure 4and the attached tractor. During greater movement of the steering wheel,the turning movement will prevent the valve member from returning to itsneutral position until the move ment of the wheel has stopped. Thepresent construction, therefore, stops rotation or turning of said frontportion of the structure and attached front tractor at an angle of turn,from any steered condition of the tractor unit in which said valvemember is in its neutral position, corresponding to the amount thesteering wheel 152 has been turned.

The interconnecting means 3 of the tractor unit supports the fronttractor 1 in a proper position so that the previously removed frontwheel bolster of the tractor can easily with an ample amount ofclearance be moved under the mounting plate or flange portion 169 of thesteering pivot shaft of the tractor for mounting thereto by means of theusual four bolts preparatory to separation of the tractor from thestructure 4 for independent use of the tractor. This supported positionof the tractor, of course, also facilitates removal of the front wheelbolster thereof during formation of the tractor unit.

Should it be desired to operate one of the tractors independently of theunit for lighter farm or other Work, the front tractor 1 can be quicklydisconnected from the unit after mounting of the front wheel bolster asabove mentioned merely by pulling the front four quick detach cotterelements 63 and 87 and knocking or pulling out the four pins 62 and 76.Such disconnection only takes a few seconds and constitutes one of theimportant features of the present invention. The front tractor is, ofcourse, readily reconnected by the reverse process.

For such independent use of the front tractor, the drawbar 105, which isthe sole drawbar of the tractor unit, is very quickly disconnectablefrom the rear tractor by removing the two pins 106 and two nuts of theeyebolts of the axle carrier brackets 99 and reconnectable within thepocket structures 46 and 50 and to the axle carrier brackets 68 of thefront tractor by insertion of the same pins and threading on of the nutsof the eyebolts of the rear portions 70 of the axle carrier brackets 68.In order to obtain the proper level of the drawbar when mounted on thefront tractor, the pins 173 of the latter are removed from the rearholes of the U-shaped members 108 and the braces 109 repinned in theforward holes 174 of said members.

Should it be desired to operate both tractors independently, thestructure 4 can be quickly and easily removed from both of the tractorsmerely by withdrawing the four connecting pins on each of the tractors,namely 62, 76, 86, and 101, after first disconnecting the two attachingbolts between the members 146 and 147 and the flange at the bottom ofthe steering pivot shaft 150 of the rear tractor and hydraulic lines and161 from the front tractor. Prior to such removal of the structure 4,the front wheel bolster of the front tractor would be mounted in placeand the rear tractor supported by suitable means as by a jack placedrearwardly of the crossmember 23. After such removal, the front wheelbolster of the rear tractor would be mounted in place while the reartractor remained supported.

For connecting the structure 4 and formation of the tractor unit, theforward tractor 1 can be conveniently backed into proper spaced relationto the rear tractor 2 while the latter is supported after removal of thefront wheel bolster thereof and the structure 4 conveniently and easilyslipped into the stirrup or pocket structures 45, 46, 47, and 48 and 49,50, 51, and 52 as by the use of jacks and pinned. The unit is completedby reconnecting the pair of connecting bolts between the members 146 and147 and the flange of the steering pivot shaft 150 of the rear tractorand reconnection of fluid lines 160 and 161.

As previously indicated, the interconnecting means 3 of the tractor unitis rigid in the longitudinal vertical plane for withstanding bendingmoments resulting from its support of the tractors forwardly of the rearwheels thereof while it permits free pivotal movement in the horizontalplane and transverse vertical plane normal to the longitudinal verticalplane to provide for turning or steering of the tractor unit and alsorelative roll between the two tractors.

It is further pointed out that the structure 4 supports each of thetractors at a midpoint which most significantly relieves the tractorstructures of all stresses in excess of those they are intended toreceive in their normal use as individual tractors as a result of theremoval of the front wheel bolsters and cantilevered arrangement of thetractors.

Also very significant, by having the rear tractor 2 supported at amidpoint with the forward portion thereof extending in unsupported,flexible cantilever fashion rather than being rigidly tied to thestructure 4 at the front, said structure not only takes the excessbending moment above indicated but also substantially all of thetorsional stress resulting from operating the tractor unit in a curvedpath or while making a turn. This torsional or twisting stress which isimposed on the structure 4 results from the bending moment previouslymentioned being set up within said structure while the forward and rearportions 5 and 6 thereof are disposed at an angle to each other due tothe turning movement of the tractor unit, thus causing the vertex of theangle formed by such portions at the medial yoke and pin portion of thestructure to swing in an arc to set up the twisting forces. Thestructure 4 therefore takes substantially all of the torsional ortwisting stress rather than the tractor structure which is not designedand intended to withstand such stress and which would otherwise fail orbe seriously damaged.

There is, of course, but a single operator of the tractor unit who sitson the rear tractor 2 and has other operating controls running to theforward tractor, but inasmuch as these controls do not form part of thepresent invention they are not disclosed.

Although it is clearly preferably to remove the front wheel bolster ofthe front tractor during formation of the tractor unit, the bolster maybe left on the tractor, if desired, if sufficient clearance is providedbetween the wheels thereof and the ground to assure that the wheels areout of contact with the ground during operation of the unit. In thiscase, of course, the interconnecting means 3 would have to be formed soas to support the front of the forward tractor in a higher position toprovide such clearance between the wheels and the ground.

Although one double-acting hydraulic cylinder has been disclosed as themotor means for producing pivotal movement between the forward andrearward portions of the structure 4', two single-acting cylinders maybe employed on opposite sides of the tandem tractor unit, respectively,for instance, or other suitable motor means may be employed, if desired.

It should be understood that although the tandem tractor unit which hasbeen illustrated and described has two tractors, such unit notnecessarily limited to two tnactors. For example, the substructure ofthe interconnecting means could extend rearwardly under a third tractorfrom which the front wheel bolster has been removed, for instance, thestructure being suitably articulated between the second and thirdtractors to permit moving of the tandem tnactor unit in curved paths asfor turning.

While reference has been made to the tractor unit as operating over theground, the same can, of course, operate on any suitable supportingsurface, indoors as well as out, and accordingly, the word ground isused in the specification and appended claims as a convenient expressionintended to cover any suitable supporting surface of tandem connectedarticles.

Although the foregoing portions of the specification have referredparticularly to tandem connected tractors and the interconnecting meanstherefor, it is not intended necessarily to limit the invention totractors inasmuch as the same is applicable to other vehicles, mobileequipment, and other articles and components for interconnection thereofin tandem so as to be movable along the ground as a unit.

It should be understood that such terms as horizontal and verticalappearing in the specification are merely relative to the position ofthe tandem tractor unit shown in the drawing, that is, when on perfectlylevel ground, and accordingly such terms in the appended claims are notto be construed in the absolute sense but rather as pertaining to thesubject tandem units of the claims when on level ground.

Although a specific, preferred form of the invention has been disclosed,modifications and other forms are had in mind and accordingly, theinvention should be limited only by the terms of the appended claims,liberally construed in the overall light of the invention in its variousaspects.

What is claimed is:

1. A mobile unit comprising a pair of components each havingground-engaging support means movable along the ground and the center ofgravity of each being longitudinally beyond said support means so thateach unconnected to the other component would tip toward the ground,connecting means interconnecting the components in tandem so as toprevent the aforesaid tipping and provide for unitarylongitudinal'movement of the components along the ground, saidconnecting means including a structure which is rigid in thelongitudinal vertical plane and articulated at a longitudinal locationfor swinging movement between the two portions thereof adjacent thearticulation in the horizontal plane, said-two portions of saidstructure being attached to the components respectively so as to permitrelative swinging movement between the components solely at the locationof articulation of said structure for permitting longitudinal movementof the unit along the ground selectively in straight and curved paths,said structure supporting each component longitudinally beyond saidsupport means in the direction of the end of the componentlongitudinally between which and said support means the center ofgravity of the component is located, actuating means comprising motormeans connected to one of said portions, means operatively connectingsaid motor means to the other of said portions for causing swingingmovement between said portions and consequently between said componentsin one direction upon movement of the second named connecting means inone direction and in the opposite direction upon movement of the secondnamed connecting means in the opposite direction, means for conductingenergy to the motor means, motor control means connected to said energyconducting means selectively operable for permitting passage of energyreceived by the control means to the motor'means through said energyconducting means for effecting movement of the second named connectingmeans and for preventing passage of energy beyond the control means forarresting swinging movement between said portions substantiallymaintaining the positions of said portions relative to each other afterthe arresting of the swinging movement between said portions, one of thecomponents having steering control'means oper atively connected to themotor control means for operating the latter for producing said swingingmovement be tween said portions.

2. The subject matter of claim 1, the end of one of the componentsbetween which end and said support means its center of gravity islocated being the end closest to the other component in the connectedcondition of the components, the support afforded by said structure tosaid one component longitudinally beyond said support means beinglongitudinally removed from said end for at least reducing twistingforces in said one component during substantially longitudinal movementof the connected components along the ground in other than a straightpath.

3. The subject matter of claim 1, each of said two portions of saidstructure being attached to its respective component by means comprisingpin means, said structure being quickly and simply removable from thecomponents when connected in tandem merely by removal of said pin means,said structure being easily connec'table to the components forconnecting the components in tandem by the reverse pinning process.

4. A construction for tandemizing two vehicles with the vehicles facingin the same direction, each vehicle having rear axle housing means andrear ground-engaging support means, the construction comprising meansfor connecting the vehicles in tandem so that during movement along theground they engage the ground solely through the rear support meansthereof, the connecting means including a structure which is rigid inthe longitudinal vertical plane and articulated at a longitudinallocation for swinging movement between the twoportions thereof adjacentthe articulation on opposite sides of the latter in the horizontalplane, said two portions of said structure being attached to thevehicles respectively so as to permit relative swinging movement betweenthe vehicles solely at the location of articulation of said structurefor permitting longitudinal movement of the tandemized vehiclesselectively in straight and curved paths, said structure supporting eachvehicle substantially forward of the rear axle housing means thereof,said forward portion supporting the front vehicle forward of its housingmeans at a single longitudinal location, sai'd rearward portionsupporting the rear vehicle forward of its housing means at a singlelongitudinal location, said longitudinal location of support of each ofthe vehicles being intermediate the front end and housing means of thevehicles and longitudinally substantially removed from each, theconnection between said two portions of said structure comprising a yokeon one of said portions, means on the other of said portions receivedwithin the yoke, and pin means extending between the yoke and said meansreceived therewithin, theforw ard portion of said structure having apair of laterally spaced forwardly extendingportions for passage underthe rear axle housing'means of the front vehicle and providing supportof the front vehicle forwardly of the rear 'axlefhousing means atopposite sides of the vehicles respectively, the rearward portion ofsaid structure having a pair of rearw'ardly extending portions forpassage under the rear vehicle which converge toward the front.

5. A construction for tandemizing two vehicles with the vehicles facingin the same direction, each vehicle having rear axle housing means andrear ground-engaging support means, the construction comprising meansfor connecting the vehicles in tandem so that during movement along theground they engage the ground solely through the rear support meansthereof, the connecting means including a structure which is rigid inthe longitudinal vertical plane and articulated at a longitudinallocation for swinging movement between the two portions thereof adjacentthe articulation on opposite sides of the latter in the horizontalplane, said two portions of said structure being attached to thevehicles respectively so as to permit relative swinging movement betweenthe vehicles solely at the location of articulation of said structurefor permitting longitudinal movement of the tandemized vehiclesselectively in straight and curved paths, said structure supporting eachvehicle substantially forward of the rear axle housing means thereof,the means for connecting the vehicles in tandem including means forconnecting the forward portion of said two portions to the rear axlehousing means of the front vehicle, means connected to said forwardportion for solely supporting, forward of said housing means of thefront vehicle, the front vehicle on said structure at a longitudinallocation which is intermediate the rear axle housing means and front endof the vehicle and substantially removed longitudinally from each, meansfor connecting the rearward portion of said two portions to the rearaxle housing means of the rear vehicle, and means connected to saidrearward portion for solely supporting, forward of said housing means ofthe rear vehicle, the rear vehicle on said structure at a longitudinallocation which is intermediate said housing means and front end of thevehicle and substantially removed longitudinally from each, said meansfor connecting the forward portion to said housing means of the frontvehicle comprising a pair of means for connection to said housing meansof the front vehicle on opposite sides of the vehicle respectively eachcomprising a pair of wall means horizontally spaced apart at the lowertermini part of which is below said housing means, said means connectedto said forward portion for solely supporting the front vehiclecomprising a pair of means for connection to the front vehicle onopposite sides of the vehicle respectively forward of said housing meansthereof each comprising a pair of wall means horizontally spaced apartat the lower termini and interconnected above said termini, said forwardportion including a pair of forwardly extending members for passingunder said housing means of the front vehicle and for extending withinthe four pairs of wall means, at least a pair of pin means extendingthrough the rear pairs of wall means respectively and the receivedmembers of said structure respectively for sole attachment of saidstructure thereto, at least a pair of pin means extending through thefront pairs of wall means respectively below the received members ofsaid structure respectively for sole retention of said structure withinsaid means, the front vehicle and connected means being quickly andsimply removable from said structure and attached rear vehicle when thevehicles are tandemized for independent use merely by removal of saidpins, the front vehicle and connected means being easily connectable tothe structure and attached rear vehicle by the reverse pinning process.

6. The subject matter of claim 5, said means for connecting the rearwardportion to said housing means of the rear vehicle comprising a pair ofmeans for connection to said housing means of the rear vehicle onopposite sides of the vehicle respectively each comprising a pair ofwall means horizontally spaced apart at the lower termini, said meansconnected to said rearward portion for solely supporting the rearvehicle comprising a pair of means for connection to the rear vehicle onopposite sides of the vehicle respectively forward of said housing meansthereof each comprising a pair of wall means horizontally spaced apartat the lower termini and interconnected above said termini, saidrearward portion including a pair of forwardly extending members forextending within the four pairs of wall means, at least a pair of pinmeans extending through the rear pairs of wall means respectively andthe received members of said structure respectively for sole attachmentof said structure thereto, at least a pair of pin means extendingthrough the front pairs of Wall means respectively below the receivedmembers of said structure respectively for sole retention of saidstructure within said means, said structure being quickly and simplyremovable from both vehicles for independent use of the vehicles merelyby removal of said pins, said structure being easily connectable to thevehicles by the reverse pinning process.

7. A construction for tandemizing two vehicles with the vehicles facingin the same direction and for turning the front vehicle for steering thetandemized vehicles, the vehicles each having rear axle housing means,rear groundengaging support means, and normally prior to tandemizing afront bolster with attached ground-engaging support means and from atleast the rear vehicle of which the front bolster and attached supportmeans are removed in the tandemized condition of the vehicles, the rearvehicle having limitedly rotatable means at least near the front thereoffor turning the front bolster normally attached to the means prior totandemizing for steering the vehicle and a steering wheel operativelyconnected to the rotatable means for rotation of the latter in eitherdirection, the construction comprising means for connecting the vehiclesin tandem so that the latter at least most of the time during movementalong the ground engage the ground solely through the rear support meansthereof, the connecting means comprising a structure which issubstantially rigid substantially in the longitudinal vertical plane andarticulated at a longitudinal location for swinging movement between thetwo portions thereof adjacent the articulation on opposite sides of thelatter substantially in the horizontal plane, said two portions of saidstructure being attached to the vehicles respectively, when the latterare tandemized, so as to permit relative swinging movcmerit between thevehicles solely at the location of articulation of said structure forpermitting substantially longitudinal movement of the tandemizedvehicles selectively in straight and curved paths, said structuresupporting each vehicle, when the vehicles are tandemized, substantiallyforward of the rear axle housing means thereof, the constructionincluding actuating means comprising motor means connected to one ofsaid portions of said structure, means operatively connecting the motormeans to the other of said portions of said structure effective to causeswinging movement of the forward portion of said two portions of saidstructure relative to the rearward portion of said two portions of saidstructure and consequently of the front vehicle relative to the rearvehicle of the tandemized vehicles, at least during substantiallylongitudinal movement of the tandemized vehicles, in one direction uponmovement of at least part of the second named connecting means in onedirection and in the opposite direction upon movement of at least partof the latter connecting means in the opposite direction, means forconducting energy to the motor means for operation of the latter, motorcontrol means connected to said means for conducting energy selectivelyoperable so as to permit passage of energy received by the control meansto at least part of the motor means through part of said means forconducting energy for elfecting movement of at least part of the secondnamed connecting means in said one direction, for effecting saidswinging movement of said forward portion relative to said rearwardportion of said structure in said one direction, so as to permit passageof energy received by the control means to at least part of the motormeans through part of said means for conducting energy for effectingmovement of at least part of the second named connecting means in saidopposite direction for effecting said swinging movement of said forwardportion relative to said rearward portion of said structure in saidopposite direction, and so as to prevent passage of energy beyond thecontrol means for arresting swinging movement of said forward portionrelative to said rearward portion of said structure during swinging;movement of the same in either direction and for substantiallymaintaining the position of said forward portion relative to said'rearward portion of said structure after the arresting of the swingingmovement of said forward portion, motor control means operatingmeansrelatively nonrotatably connectible to said rotatable means of the rearvehicle and operatively connected to the motor control means effectiveto operate the latter so as to produce said swinging movement of saidforward portion relative to said rearward portion of said structure insaid one direction upon appreciable turning of the steering wheel of therear vehicle of the tandemized vehicles in one direction and so as toproduce said swinging movement of said forward portion relative to saidrearward portion of said structure in said opposite direction uponappreciable turning of said steering wheel in the other direction, themotor control means being connected to said rearward portion of saidstructure, and means connecting said forward portion of said structureand the motor control means operating means effective through the latterto operate the motor control means so as to arrest swinging movement ofsaid forward portion relative to said rearward portion of said structurein either direction and prevent further swinging movement thereof untilfurther operation of the motor control means upon the swinging movementbringing said forward portion of said structure to a position relativeto said rearward portion of said structure substantially correspondingto the position in which said steering wheel has been placed by theoperator of the tandemized vehicles.

8. The subject matter of claim 7, the support afforded by said structureto the rear vehicle forward of said housing means thereof being at leastsubstantially to the rear of the front end of the vehicle for at leastsubstantially reducing twisting forces in the rear vehicle duringmovement of the tandemized vehicles in other than a straight path.

9. A construction for tandemizing two vehicles with the vehicles facingin the same direction and for turning the front vehicle for steering thetandemized vehicles, the vehicles each having rear axle housing means,rear groundengaging support means, and normally prior to tandemizing afront bolster with attached ground-engaging support means and from atleast the rear vehicle of which the front bolster and attached supportmeans are removed in the tandemized condition of the vehicles, the rearvehicle having limitedly rotatable means at least near the front thereoffor turning the front bolster normally attached to the means prior totandemizing for steering the vehicle and a steering wheel operativelyconnected to the rotatable means for rotation of the latter in eitherdirection, the construction comprising means for connecting the vehiclesin tandem so that the latter at least most of the time during movementalong the ground engage the ground solely through the rear support meansthereof, the connecting means comprising a structure which issubstantially rigid substantially in the longitudinal vertical plane andarticulated at a longitudinal location for swinging movement between thetwo portions thereof adjacent the articulation on opposite sides of thelatter substantially in the horizontal plane, said two portions of saidstructure being attached to the vehicles respectively, when the latterare tandemized, so as to permit relative swinging movement between thevehicles solely at the location of articulation of said structure forpermitting substantially longitudinal movement of the tandemizedvehicles selectively in straight and curved paths, said structuresupporting each vehicle, when the vehicles are tandemized, substantiallyforward of the rear axle housing means thereof, the constructionincluding actuating means commotor means connected to one of saidportions of said structure, means operatively connecting the motor meansto the other of said portions of said structure effective to causeswinging movement ofthe forward portion of said two portions of saidstructure relative to the rearward portion of said two portions of saidstructure and consequently of the front vehicle relative to the rearvehicle of the tandemized vehicles, at least during substantiallylongitudinal movement of the tandemized vehicles, in one direction uponoperation of the motor means in one direction and in the oppositedirection upon operation of the motor means in the opposite direction,means for conducting energy to the motor means for operation of thelatter, motor control means connected to said means for conductingenergy selectively operable so as to permit passage of energy receivedby the control eans to the motor means through part of said means forconducting energy for opera-ting the motor means in said one directionfor said swinging movement of said forward portion relative to saidrearward portion of said structure in said one direction, so as topermit passage of energy received by the control means to the motormeans through part of said means for conducting energy for operating themotor means in said opposite direction for said swinging movement ofsaid forward portion relative to said rearward portion of said structurein said opposite direction, and so as to prevent passage of energybeyond the control means for arresting operation of the motor means ineither direction and consequently swinging movement of said forwardportion relative to said rearward portion of said structure duringswinging movement of the same in either direction and for substantiallymaintaining the position of said forward portion relative to saidrearward portion of said structure after the arresting of the swingingmovement of said forward portion, motor control means operating meansrelatively nonrotatably connectible to said rotatable means of the rearvehicle and operatively connected to the motor control means effectiveto operate the latter so as to produce said swinging movement of saidforward portion relative to said rearward portion of said structure insaid one direction upon appreciable turning of the steering wheel of therear vehicle of the tandemized vehicles in one direction and .so as toproduce said swinging movement of said forward portion relative to saidrearward portion of said structure in said opposite direction uponappreciable turning of said steering wheel in the other direction, themotor control means being connected to said rearward portion of saidstructure, and means connecting said forward portion Olf said structureand the motor control means operati-ng means effective through thelatter to operate the motor control means so as to arrest swingingmovement of said forward portion relative to said rearward portion ofsaid structure in either direction and prevent further swinging movementthereof until further operation of the motor control means of saidstructure to a position relative to said rearward portion of saidstructure substantially corresponding to the position in which saidsteering wheel has been placed by the operator of the tandemizedvehicles.

prising 10. In combination with a pair of tractors from which the frontwheel bolsters have been removed; connecting means for hitching thetractors in tandem so that steering may be accomplished from the reartractor, said connecting means comprising a forward portion supportingthe front tractor in proximity to its center of gravity, a rear portionsupporting the rear tractor in proximity to its center of gravity, andan intermediate portion connected to the front portion pivotally in thevertical transverse plane and connected to the rear portion pivotally inthe horizontal plane; power means mounted on the rear portion andconnected with the intermediate portion for pivoting the intermediateportion in the horizontal plane; control means responsive to steering ofthe rear tractor for engaging the power means; and followup means re-References Cited in the file of this patent UNITED STATES PATENTS WellsJune 28, 1932 Wright Dec. 20, 1955 Gaspardo Aug. 26, 1958 ROCklWCll May5, 1959 Toth July 28, 1959 Gar-man Nov. 29, 1960

1. A MOBILE UNIT COMPRISING A PAIR OF COMPONENTS EACH HAVING GROUND-ENGAGING SUPPORT MEANS MOVABLE ALONG THE GROUND AND THE CENTER OF GRAVITY OF EACH BEING LONGITUDINALLY BEYOND SAID SUPPORT MEANS SO THAT EACH UNCONNECTED TO THE OTHER COMPONENT WOULD TIP TOWARD THE GROUND, CONNECTING MEANS INTERCONNECTING THE COMPONENTS IN TANDEM SO AS TO PREVENT THE AFORESAID TIPPING AND PROVIDE FOR UNITARY LONGITUDINAL MOVEMENT OF THE COMPONENTS ALONG THE GROUND, SAID CONNECTING MEANS INCLUDING A STRUCTURE WHICH IS RIGID IN THE LONGITUDINAL VERTICAL PLANE AND ARTICULATED AT A LONGITUDINAL LOCATION FOR SWINGING MOVEMENT BETWEEN THE TWO PORTIONS THEREOF ADJACENT THE ARTICULATION IN THE HORIZONTAL PLANE, SAID TWO PORTIONS OF SAID STRUCTURE BEING ATTACHED TO THE COMPONENTS RESPECTIVELY SO AS TO PERMIT RELATIVE SWINGING MOVEMENT BETWEEN THE COMPONENTS SOLELY AT THE LOCATION OF ARTICULATION OF SAID STRUCTURE FOR PERMITTING LONGITUDINAL MOVEMENT OF THE UNIT ALONG THE GROUND SELECTIVELY IN STRAIGHT AND CURVED PATHS, SAID STRUCTURE SUPPORTING EACH COMPONENT LONGITUDINALLY BEYOND SAID SUPPORT MEANS IN THE DIRECTION OF THE END OF THE COMPONENT LONGITUDINALLY BETWEEN WHICH AND SAID SUPPORT MEANS THE CENTER OF GRAVITY OF THE COMPONENT IS LOCATED, ACTUATING MEANS COMPRISING MOTOR MEANS 